Glass grinding and polishing method and apparatus



Feb. 5, 1957 E. LAVERDISSE 2,730,038

GLASS GRINDING AND POLISHING METHOD AND APPARATUS Filed Sept. 7. 1955 2Sheets-Sheet l Feb. 5, 1957 E. LAVERDISSE 2,780,038

GLASS GRINDING AND POLISHING METHOD AND APPARATUS Filed Sept. 7. 1955 2Sheets-Sheet 2 GLASS GRINDING AND POLISHING METHOD AND APPARATUS EdmondLaverdisse, Auvelais, Belgium, assignor to-Les Glaceries de la Sambre,Societe Anonyme, Auvelais, Belgium, a Belgian company ApplicationSeptember 7, 1955, Serial No. 532,931 Claims priority, applicationBelgium September 8, 1954 10 Claims. (Cl. 51-110) The present inventionrelates to apparatus for grinding glass.

The invention provides an improvement in the feeding of abrasive to theiron, that is to say, the rotatory discoid tools employed for thegrinding of the lower face of continuous glass plates or sheets,according to parent Pat ent No. 2,699,021.

It also concerns an extension of the improved feeding of abrasive to therotatory polishing tools.

It is an object of the present invention to provide a method and meansenabling the abrasive mixture introduced into the interior of thegrinding or polishing tool to leave the said tool, wholly or in partwithout passing between the working face of the tool and the glass, soas to ensure continuity of the circulation of the abrasive mixturebetween the interior of the tool and the outside, regardless of theintensity of the centrifugal force acting within the tool.

The abrasive mixture which, without passing between the working face ofthe tool and the glass, leaves the interior of the tools supported bythe successive beams of a machine for working the surface of acontinuous sheet of glass, is directed together with the abrasivemixture which passes between the working face of the tool and the glass,by means of a common circulating device, towards a device with the aidof which the abrasive is graded in accordance with the grain sizes to beseparated, and the graded abrasive mixtures are each separately fed, bymeans of a separating distributing device, which is preferablyadjustable, to the different tools supported by the successive beams.

The present invention also concerns the devices for carrying out thisimproved feeding method.

A constructional form of a device designed in accord ance with theinvention is illustrated by way of example in the accompanying drawingsin which:

Figure l is a sectional elevation of the apparatus,

Figure 2 is a plan View on the line II-II of Figure 1,

Figures 3, 4, 5 and 6 are a plan view and axial sectional views of aniron constructed in accordance with the invention,

Figures 7 and 8 are an axial section and a plan view of a polishing tooldesigned in accordance with the invention, and

Figure 9 is an end view of a cording to Figure 1.

The tubular shafts 1 of the irons 2 are mounted in the upper and lowerbearings 3, 4 fast with the beam 5, and rest through the hub 6 of a wormwheel 7 fast with each tubular shaft 1 on the lower bearing 4. The wormwheels 7 are driven with the aid of a common worm 8 by a part of theassembly acnited States Patent motor 9 mounted on the bottom of thebeam. The tubular shaft 1 of each iron leads at one end into the centralpart 10 of the iron and at the other end into a collecting tank 11secured to the bottom of the beam. Disposed within each tubular shaft 1is a fixed tube 12 extending in fluidtight fashion through the base ofthe collecting tank 11,

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which supports it, and opening at its upper end, at which it is providedwith a head forming a spreading cap 13, into the central part it of theiron. The tubular shaft 1 and the fixed tube 12 are separated from oneanother by an annular channel 14 of relatively large cross-section whichleads at one end into the central chamber 10 of the iron and at theother end into the collecting tank 11. The coliecting tank ll preferablyhas an inclined base 15 and is provided at its lowermost point with adischarge pipe 16 leading into a reservoir 17. The abrasive mixture,which passes from the centre of the tools between the working surface ofthe latter and the glass to the outside is collected on collectingplates 54, which direct it towards the collecting tanks 55, and returnsfrom the latter through the pipes 56, also to the reservoir 17. Thelatter is fed with abrasive mixture (water and fresh or used sand, orpolishing composition) through a feed duct 18 and is connected at theother end to a pump 19, by which the abrasive mxiture is deliveredthrough a pipe 20 into the grading tanks 21, 22, 23.

The abrasives, for example sand, in suspension in water, are graded bythe speed of the current of abrasive mixture entering at 21 and arecollected, the coarsest in the point 21 of 21, the medium-size in thepoint 22 of 22,

' and the finest in the point 23' of 23. Each of the points The gradingtank 23 is provided with an overflow 27 for the discharge of the excessof abrasive mixture, for example, towards the collecting reservoir 17'.

For the sake of simplicity, only the distributor fed by 26 isillustrated in the drawings.

This distributor comprises a cistern 28 suspended in such manner as tobe able to turn on a pin 29 controlled by any appropriate transmissionsystem, for example, a pulley transmission system comprising pulleys 30,31 and a belt 32. The cistern 23 is provided, for example, with two ormore transfer pipes 33, 34 through which the abra sive mixture isdistributed in a tank 35 divided by angularly displaceable partitions36, 37, 33 (see Figure 2) into a number of compartments, in the presentcase three, 39, 4t), 41, the number of such compartments beingdetermined by the number of tools to be fed on one beam. The base ofeach or" the compartments 39, id, 41 has an outlet 42, 43, 44respectively through each of which the abrasive mixture is transferredinto one of the funnels 45, 46, 47 each connected by a flexible pipe 48to the feed duct 12 of the corresponding tool 2.

The distribution of the abrasive mixture between the tools 2 is adjustedby angularly displacing the partitions 36, 37, 38 in such manner as tovary proportionally the arcs a, b, 0 (see Figure 2) and thus the timefor which it stays in the compartments 39, 5d, 41 below the pipes 33, 34for the transfer thereof from the distributing cistern 28, which isactuated with a continuous rotatory movement.

The distributing tank 35 is provided with an overflow 49 leading to thecollecting reservoir 17.

During the working, the beams 5 and the tools 2 supported thereby areactuated with a transverse reciprocating movement in relation to thelongitudinal direction of the glass sheet 50. The tools also receive arotational movement, by reason of which the central cup 51 of the tools,constituting the base of the central chamber 10 of the latter andprovided with the projecting and dis ribstias bl de 5 m a ts 9 tabrasive mixture ed into the central chamber 19 a centrifugal forcewhich varies with the speed of rotation of the tools or of the cup 53,if the latter receives a rotational movement independent of that of theactual tool 2, as is the case with the tool illustrated on theright-hand end of the beam 5 (Figure 1).

The feeding takes place as follows:

The pump 19 and the distributing cup being as sumed to be in operation,if the tools 2 are stationary (Figure 4) and their angular velocity isconsequently zero, the abrasive mixture penetrates therein through theduct, 12, is spread on cap 13, falls into the cup 53, 52 and descendsthrough the annular duct 14 into the collecting tank 11, whence itreturns through the discharge pipe 16 into the reservoir 17. Theabrasive in ture is taken up from the latter by the pump which deliversit through pipe 2% into the grading tanks 23., 2.5;, 23 whence itpassesthrough the parts 26, 23, 35, 45, and returns into the tube 12, and soon.

The abrasive becomes finer as it works. As it is sorted into constantlyfiner grades (see above) in proportion as it passes through theapparatus, it is thus fed to the tools which, considered in thedirection of movement of the sheet, that is to say, from the first beamtowards the last, work the glass and leave thereon traces of constantlydecreasing depth.

When the tools 2 commence to work (see Figure 5) their speed of rotationincreases progressively. Thus, the centrifugal force to which theabrasive mixture is subjected at 51, 52 or 53 increases, and inproportion with the acceleration of the rotation of the tools 2 or ofthe cup 53, a constantly increasing proportion of the abrasive mixtureis directed towards the working plane of the tools, while a portionreturns from the tool through the duct 14 towards the r e-circulationcircuit described in the foregoing.

Finally, when the tools reach working speed (Figure 6), all the abrasivemixture entering the tools through the ducts 12 is directed towards theworking plane of the tools.

The continuity of the circulation of the abrasive mixture effected inaccordance with the present invention prevents very effectively thedeposition of the abrasive in the piping, and even throughout itstravel, and consequently all irregularities in circulation, includingcomplete stoppages thereof and the dan rs resulting therefrom.

The circulating method and arrangement hereinbefore described are alsoapplicable to polishing tools of the type illustrated in Figures '7 and8.

These polishing tools comprise a metal disc or plate 56 fixed on the cup51, 52 and supporting on its upper face an annular felt disc 57 havingslots 68 and 69 formed therein in staggered relationship to one another.Assuming that the polishing tool rotates in the direction of the arrowx, the polishing composition (mixture of iron oxide and water) forced.through the cup 51, 5?. into the lower slots is thus introduced betweenthe glass and the tool and thereafter passes partly through the outerslots 6? to feed the outer part of the felt discs 67.

Modified constructions are obviously possible without departing from thescope of the invention. For example, the feed device according to theinvention may be used without the interposition of the grading tanks2.1--23, and it may be used for supplying the felt polishing discs withwater instead of the abrasive mixture.

In these two cases, the pipe it? may be provided with a shut-off valve57 and a branch 58 connected by means of a flexible pipe 5'9 to a branch6% having a shut-oil valve 61 in the piping 12. In addition, the pump 1?may be connected to the reservoir l? by a pipe 62 pro vided with ashutoff valve as and to a water reservoir (not shown) by a pipe asprovided with a shut-off valve 65. When the valves 63 and 57 are opened,and the valves 65 and 61 are closed, the abrasive mixture is 4 l d ocirculate a lisrsinbefm dessribsd the valve 57 is closed and, the valve61 is opened, the abrasive mixture will pass through the tools and willreturn to the reservoir 17 through the pipes '16 and 56 without passingthrough the grading tanks 2l--23. When the valve 63 is closed and thevalve 65 is opened, water, instead of abrasive mixture, will passthrough the tools without passing through the grading tanks. This water,instead of being discharged into the reservoir 17, may be directedelsewhere, for example into an abrasive-recovcry tank (not shown), withthe aid of appropriate branches (not shown) extending from the pipes 16and 56, or by means of an orientable arrangement of the latter.

Furthermore, for the polishing, the grading tanks may be completelyomitted and replaced, for example, by a conical reservoir, because it isunnecessary to grade the iron oxide which serves as an abrasive in thepolishing. After having passed through the tools, this oxide could alsobe sent to the drain duct, or into a recovery device, with the aid of apiping such as 58, 59, 60, 61, 12 and 16, 56 described in the foregoing.

I claim:

1. The method of feeding abrasive mixture to the rotary tools ofapparatus for working the lower face of a continuous glass sheet; saidmethod comprising the steps of withdrawing the abrasive mixture from areservoir therefor, supplying the withdrawn mixture to the interior saidrotary tools axially of the latter, centrifugally distributing a portionof the mixture supplied to said tools between the working faces of thelatter and the lower face of the glass sheet, and returning theremainder of the mixture axially from the interior of the tools to thereservoir in a continuous cycle, the relative proportions of the mixturesupplied to said tools which are distributed between the working facesof the latter and the lower face of the glass sheet and returned to saidreservoir, respectively, being determined by the rotational speed ofsaid tools so that the rate of circulation of the mixture in saidcontinuous cycle may be relatively great to prevent clogging of thelatter even when the tools are rotating slowly and require a relativelysmall feed of mixture between their working faces and the lower face ofthe glass sheet. 7 H

2. The method of feeding abrasive mixture to the rotary tools ofapparatus for working the lower surface of a continuous glass sheet;said method comprising the steps of pumping abrasive mixture from areservoir thereof, grading the pumped mixture according to the grainsize of the abrasive therein, distributing the graded mixture to therotary tools. in accordance with the positions of the latter in theapparatus, feeding the distributed mixture to the interiors of therelated tools axially of the latter, centrifugally spreading a portionof the mixture fed to the interior of each tool for radially outwardpassage between the working face of the tool and the lower surface ofthe glass sheet; while axially withdrawing from the interior of eachtool the remainder of the mixture fed thereto, and returning to thereservoir, in a continuous cycle, said remainder of the mixturewithdrawn axially from each tool, the used mixture that has completedits radial passage between said Working face of the tool and the lowersurface of the glass sheet and any mix ture that has been graded in anamount exceeding the quantities that are distributed to the tools, sothat the rate of passage. of the mixture in said continuous cycle isindependent of the quantities that pass between the working faces of thetools and the lower surface of the glass sheet.

3. In apparatus for working the lower surface of a continuous glasssheet; the combination of tools rotatable about vertical axes and havingworking faces at the tops thereof, a reservoir for an abrasive mixtureto be supplied to said tools, means continuously pumping abrasivemixture from said reservoir, means distributing the pumped mixture amongsaid tools, means axially admitting the distributed mixture to theinterior of each of said tools at the center of the latter, each of saidtools having means centrifugally spreading a portion of the mixtureadmitted to the interior thereof for passage, in a generally radiallyoutward direction, between said working face of the tool and the lowersurface of the glass sheet, means axially discharging from the in teriorof each tool the remainder of the mixture admitted to the latter so thatthe amounts of mixture passing between said working faces and the lowersurface of the glass sheet are independent of the amounts admitted tothe tools, collector means receiving both the portion of the mixturepassing between the working face of each tool and the lower surface ofthe glass sheet and the remainder of the admitted mixture dischargedaxially from each tool, and return means carrying the mixture from saidcollector means back to said reservoir so that a continuous cycle existsfor the mixture and the rate of flow therein can be substantial toprevent clogging even when only very small quantities of mixture are topass between the working faces of the tools and the lower face of theglass sheet.

4. In apparatus for working the lower surface of a continuous glasssheet; the combination as in claim 3, wherein said working face of eachof said tools has a series of circular, spaced apart grooves thereinconcentric with its axis of rotation and radial grooves extendingbetween successive circular grooves and disposed in circumferentiallystaggered relation.

5. In apparatus for working the lower surface of a continuous glasssheet; the combination as in claim 3, wherein each of said tools has afelt pad in the shape of a broad annulus mounted on the top thereof todefine said working face thereof, said pad having inner and outer,radially extending series of slots therein opening at the inner andouter peripheries, respectively, of said annulus, the slots of saidinner and outer series being circumferentially staggered relative toeach other.

6. In apparatus for working the lower surface of a continuous glasssheet; the combination as in claim 3, wherein said means admitting themixture to the interior of each tool includes a first pipe extendingaxially into the tool from the bottom of the latter, said first pipehaving an upper open end within the interior of the tool and a radiallyoutward directed flange at said upper open end across which the mixtureis admitted from said first pipe, said means axially discharging theremainder of the admitted mixture from each tool includes a second pipetelescoping over said first pipe and of larger diameter than the latterto define an annular space between said first and second pipes opening,at its upper end, and said centrifugal spreading means includes anupwardly open, cup-shaped member at the upper end of said second pipehaving impeller blades therein and rotated at a speed proportional tothe rotational speed of the related tool so that, as the mixture isadmitted across said radial flange of the first pipe, the admittedmixture is subject to the centrifugal action of said blades tending tocause radially outward fiow of the mixture from said cup-shaped memberand to gravitational force tending to cause downward discharge of themixture from said cup-shaped member into said annular space between saidfirst and second pipes.

7. In apparatus for working the lower surface of a continuous glasssheet; the combination as in claim 6, wherein said cup-shaped member andsecond pipe are fixed relative to said tool to rotate with the latter,and said second pipe acts as a supporting shaft for the related tool.

8. In apparatus for working the lower surface of a continuous glasssheet; the combination as in claim 6, wherein said cup-shaped member andsaid second pipe are rotatable together relative to the related tool,and further comprising means rotating said second pipe in response torotation of the related tool at a speed different from the rotationalspeed of the related tool.

9. In apparatus for working the lower surface of a continuous glasssheet; the combination of tools rotatable about vertical axes and havingworking faces at the tops thereof, a reservoir for an abrasive mixtureto be supplied to said tools and having an outlet, pump means forwithdrawing abrasive mixture from said outlet of the reservoir, pipemeans receiving the abrasive mixture pumped from said reservoir, gradingmeans receiving the abrasive mixture from said pipe means and operativeto grade the mixture according to grain size, distributor meansreceiving graded abrasive mixture from said grading means and operativeto distribute predetermined portions of the graded abrasive mixture forfeeding to the related tools, means axially admitting the distributedmixture to the interior of each of said tools and the center of thelatter, cach of said tools having means centrifugally spreading aportion of the mixture admitted to the interior thereof for passage, ina generally radially outward direction, between said working face of thetool and the lower surface of the glass sheet, means axially dischargingfrom the interior of each tool the remainder of the mixture admitted tothe latter so that the amounts of mixture passing between said workingfaces and the lower surface of the glass sheet are independent of theamounts admitted to the tools, collector means receiving both theportion of the mixture passing between the working face of each tool andthe lower surface of the glass sheet and the remainder of the admittedmixture discharged axially from each tool, and return means carrying themixture from said collector means back to said reservoir so that acontinuous cycle exists for the mixture and the rate of flow therein canbe substantial to prevent clogging even when only very small quantitiesof mixture are to pass between the working faces of the tools and thelower face of the glass sheet.

10. In apparatus for working the lower surface of a continuous glasssheet; the combination as in claim 9, further comprising first valvemeans in the outlet from the reservoir, a water supply pipe connected tothe inlet side of said pump means, second valve means in said watersupply pipe, third valve means in said pipe means between said pumpmeans and grading means, by-pass ipe means connected, at one end, to thefirst mentioned pipe means between said pump means and third valve meansand, at the other end, to said means axially admitting the distributedmixture to said tools, and fourth valve means in said by-pass pipemeans.

References Cited in the file of this patent

